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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108/* * Copyright 2019 Advanced Micro Devices, Inc. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. * */#include <linux/semaphore.h>#include <linux/atomic.h>
/* * Reusable 2 PHASE task barrier (rendez-vous point) implementation for N tasks. * Based on the Little book of semaphores - https://greenteapress.com/wp/semaphores/ */
#ifndef DRM_TASK_BARRIER_H_#define DRM_TASK_BARRIER_H_
/* * Represents an instance of a task barrier. */struct task_barrier { unsigned int n; atomic_t count; struct semaphore enter_turnstile; struct semaphore exit_turnstile;};
static inline void task_barrier_signal_turnstile(struct semaphore *turnstile, unsigned int n){ int i;
for (i = 0 ; i < n; i++) up(turnstile);}
static inline void task_barrier_init(struct task_barrier *tb){ tb->n = 0; atomic_set(&tb->count, 0); sema_init(&tb->enter_turnstile, 0); sema_init(&tb->exit_turnstile, 0);}
static inline void task_barrier_add_task(struct task_barrier *tb){ tb->n++;}
static inline void task_barrier_rem_task(struct task_barrier *tb){ tb->n--;}
/* * Lines up all the threads BEFORE the critical point. * * When all thread passed this code the entry barrier is back to locked state. */static inline void task_barrier_enter(struct task_barrier *tb){ if (atomic_inc_return(&tb->count) == tb->n) task_barrier_signal_turnstile(&tb->enter_turnstile, tb->n);
down(&tb->enter_turnstile);}
/* * Lines up all the threads AFTER the critical point. * * This function is used to avoid any one thread running ahead if the barrier is * used repeatedly . */static inline void task_barrier_exit(struct task_barrier *tb){ if (atomic_dec_return(&tb->count) == 0) task_barrier_signal_turnstile(&tb->exit_turnstile, tb->n);
down(&tb->exit_turnstile);}
/* Convinieince function when nothing to be done in between entry and exit */static inline void task_barrier_full(struct task_barrier *tb){ task_barrier_enter(tb); task_barrier_exit(tb);}
#endif